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I think the thing that honestly puzzles me is: before physicists learned physics, did their entire desire to be in the field spring from “shut up and calculate”

I think the thing that honestly puzzles me is: before physicists learned physics, did their entire desire to be in the field spring from “shut up and calculate”? Or was there a time in their lives (especially when they were young) where they thought (or felt) a desire to get into physics to understand the underlying mechanisms that drive the universe? I feel like, at least for some people, the second thing must have been true. So, given that most quantum physicists seem uninterested in interpretations, where did this desire go? Did it disappear? Did the field get them to stop caring? Did it feel silly to them at some point? Did it feel hopeless? Or something else? I genuinely want to know.

lambdatronics 5y ago
There are a broad range of motivations. In my case: - I wanted to work on nuclear fusion energy, for the future of humanity. - I was told that if I had a PhD in physics, I could do just about anything - it's a way of keeping options open. - I liked tinkering in the lab & learning new mind-expanding concepts in textbooks. - I viewed it as a test of my intelligence. (Turns out, it's more about perseverance.) I know at least one string theorist, and they seem to be motivated primarily by liking to mess around with abstruse mathematics. Some others seem to enjoy the 'nerd cred.' I think the ones whose sole motivation is 'getting to the bottom of the universe' probably burn out early, b/c there's so little of that to be had right now. (I've heard from several people who got their PhDs in particle physics who went on to do data science/programming, saying that the field is depressing and that's why they didn't pursue it further.) As for me, I found the 'shut-up-and-calculate' attitude a major turn-off to studying quantum physics. (Plasma physics uses little or no QM, so that worked out for me.)
- lenocinor 5y ago
  I never thought about all these other motivations. Thanks for responding with them! And it sounds like there may be at some physicists like I was describing that get burnt out or discouraged too.
cevi 5y ago
The interpretations don't tell you anything that the calculations didn't tell you already (if an interpretation of quantum mechanics ever predicts something different from what quantum mechanics predicts, then it can be ruled out empirically by performing the appropriate experiment). Interpretations which don't give you a faster way to get to the results of those calculations just waste your time and get in the way of understanding. Theoretical computer science indicates that there is no significantly faster way to get the results of many of those calculations - no matter how elegant the interpretation feels, at best you have to do the same amount of work to get the same answers about what will actually happen in reality, and at worst you end up computing a million irrelevant details about things the interpretation invented which have no real-world consequence. Someone who is genuinely interested in understanding the way the world works ends up asking questions about what goes into the calculations - what's the Lagrangian, how many degrees of freedom (i.e. quantum fields) are there, what symmetries or constraints are satisfied by the laws of physics, how can we set up the math to avoid pathological situations where the results of our computations are infinite, and so on. Philosophically motivated interpretations of quantum mechanics shed exactly zero light on these questions. Well.. there is a caveat. If quantum mechanics was somehow incorrect - that is, if unitary evolution of a state vector in a Hilbert space didn't actually describe reality at all - then all of the above would be wrong. But in that case, every single interpretation of quantum mechanics would be wrong as well. Quantum computers would just flat out not work.
- lenocinor 5y ago
  Thanks for taking the time to respond. I can see the perspective (at least currently) of “the interpretations don’t add any meaningful information” being the reason not to be interested.

lambdatronics 5y ago

There are a broad range of motivations. In my case: - I wanted to work on nuclear fusion energy, for the future of humanity. - I was told that if I had a PhD in physics, I could do just about anything - it's a way of keeping options open. - I liked tinkering in the lab & learning new mind-expanding concepts in textbooks. - I viewed it as a test of my intelligence. (Turns out, it's more about perseverance.) I know at least one string theorist, and they seem to be motivated primarily by liking to mess around with abstruse mathematics. Some others seem to enjoy the 'nerd cred.' I think the ones whose sole motivation is 'getting to the bottom of the universe' probably burn out early, b/c there's so little of that to be had right now. (I've heard from several people who got their PhDs in particle physics who went on to do data science/programming, saying that the field is depressing and that's why they didn't pursue it further.) As for me, I found the 'shut-up-and-calculate' attitude a major turn-off to studying quantum physics. (Plasma physics uses little or no QM, so that worked out for me.)

lenocinor 5y ago
I never thought about all these other motivations. Thanks for responding with them! And it sounds like there may be at some physicists like I was describing that get burnt out or discouraged too.

cevi 5y ago

The interpretations don't tell you anything that the calculations didn't tell you already (if an interpretation of quantum mechanics ever predicts something different from what quantum mechanics predicts, then it can be ruled out empirically by performing the appropriate experiment). Interpretations which don't give you a faster way to get to the results of those calculations just waste your time and get in the way of understanding. Theoretical computer science indicates that there is no significantly faster way to get the results of many of those calculations - no matter how elegant the interpretation feels, at best you have to do the same amount of work to get the same answers about what will actually happen in reality, and at worst you end up computing a million irrelevant details about things the interpretation invented which have no real-world consequence. Someone who is genuinely interested in understanding the way the world works ends up asking questions about what goes into the calculations - what's the Lagrangian, how many degrees of freedom (i.e. quantum fields) are there, what symmetries or constraints are satisfied by the laws of physics, how can we set up the math to avoid pathological situations where the results of our computations are infinite, and so on. Philosophically motivated interpretations of quantum mechanics shed exactly zero light on these questions. Well.. there is a caveat. If quantum mechanics was somehow incorrect - that is, if unitary evolution of a state vector in a Hilbert space didn't actually describe reality at all - then all of the above would be wrong. But in that case, every single interpretation of quantum mechanics would be wrong as well. Quantum computers would just flat out not work.

lenocinor 5y ago
Thanks for taking the time to respond. I can see the perspective (at least currently) of “the interpretations don’t add any meaningful information” being the reason not to be interested.